Gate release version consistency

[biru-codeastromer]

Summary

• make project.version authoritative across runtime __version__, the locked project entry, and the README install tag
• require matching changelog, support line, API compatibility, manifest compatibility, and delivered-roadmap declarations
• run the audit from make check and document the atomic release-update set

Evidence

• make release-gate: 103 passed, 1 optional skip, 91.83% coverage
• the live repository passes the version audit
• nine focused tests cover the consistent fixture and one targeted diagnostic for every drifted surface
• repository audit, text policy, clean wheel install, dependency audit, example workflow, and Gitleaks passed

This PR is independent of #22-#27 and is ready for maintainer review.

[biru-codeastromer]

Superseded by merged #41, which preserves this change in the protected v0.4.0 release stack.